The invention pertains to a conveyor device with a conveyor belt for transporting workpieces from a cutting or punching machine and with a star-shaped delivery element connected to the outlet end of the conveyor belt for placing the horizontally received workpieces upright.
EP 338 297 B1 discloses a conveyor device that aligns circular workpieces punched out of a material strip with minimal punching waste relative to one another in columns and rows. These aligned workpieces can then be easily stacked and packaged. In methods of this type, the workpieces are usually transferred from the conveyor belt to a star-shaped delivery element by means of acceleration rollers, wherein the workpieces are placed upright into an essentially vertical alignment from the horizontal alignment by the star-shaped delivery element and stacked as well as packaged in this upright position. In the manufacture of wadding pads in particular, it had been determined that the pads are damaged or at least deformed by the acceleration rollers during the transfer of the wadding pads from the conveyor belt to the star-shaped delivery element and/or that the pads are introduced into the star-shaped delivery element in an inaccurate or improperly spaced fashion. Consequently, this method is not or is only conditionally suitable for workpieces of this type.
The invention is based on the objective of providing a conveyor device that allows easy stacking of workpieces with the least possible damage such that they can be supplied to a packaging machine.
According to the invention, this objective is attained by a conveying and guiding unit that takes hold of the workpieces on the lower and/or upper side and is provided between the conveyor belt and the star-shaped delivery element, by a conveying and guiding unit that has essentially the same conveying speed as the conveyor belt and the star-shaped delivery element, and by a conveying and guiding unit that is arranged in such a way that it guides the workpieces into the receptacles of the star-shaped delivery element.
The design of the conveyor device in accordance with the invention provides the substantial advantage that the workpieces are transferred from the conveyor belt to the conveying and guiding unit at a constant speed, and thus the workpieces are treated more carefully than during an accelerated transfer. In addition, a targeted guidance is achieved due to the contact of the conveying and guiding unit with the upper side as well as the lower side of the workpiece such that the workpiece is precisely placed into the star-shaped delivery element. This means that the workpieces are guided into the receptacles of the star-shaped delivery element and not thrown or flung into the delivery element as is the case with the state of the art. Since the workpieces are not accelerated, the workpieces do not have to be decelerated and the workpieces are uniformly transferred from the conveyor belt into the star-shaped delivery element by the conveying and guiding unit. Since no changes in speed are required, i.e., since no acceleration and no deceleration of the workpieces occurs, the machine is able to operate at higher speeds, so that the material throughput of the device according to the invention is higher than in comparable devices known from the state of the art.
According to one refinement of the invention, it is proposed that the conveying and guiding unit be formed by a lower and an upper conveyor band, wherein the conveyor band is formed by at least two rings, in particular, O-rings, that are arranged adjacent to one another. This provides the significant advantage that planar conveying forces transmitted onto the workpiece and the conveyor bands only need to apply minimal force to the workpieces. Due to the division of the conveyor band into conveyor strips or O-rings, the conveyor band can be easily moved into the region between the receptacles of the star-shaped delivery element which, in particular, are formed by receptacle fingers. The transfer of the workpieces from the conveyor bands to the star-shaped delivery element can be easily realized in this fashion.
According to one variant of the invention, it is proposed that the starshaped delivery element and the upper and the lower conveyor bands feature separate drives. In order to prevent differential conveying speeds between the upper and the lower conveyor bands, these components are provided with a common drive in another embodiment of the invention. It is also proposed that the star-shaped delivery element and the conveying and guiding unit are provided with a common drive in order to ensure that the workpiece is not accelerated or decelerated during the transfer of the workpieces from the conveyor bands to the star-shaped delivery element. The common drive is, in particular, formed by a driving belt that is placed around the drive elements of the conveying and guiding unit and the star-shaped delivery element, respectively.
According to one embodiment, it is proposed that the star-shaped delivery element is driven by the conveying and guiding unit. This provides the significant advantage that, if fluctuations in the conveying speed occur, such fluctuations are transferred to the star-shaped delivery element by the conveying and guiding unit so that relative synchronization is preserved.
A receptacle, into which the workpieces are successively deposited in an upright fashion, is preferably arranged at the outlet of the star-shaped delivery element, where the workpieces assume an essentially vertical position. This receptacle contains a slotted end. The conveyor fingers of the star-shaped delivery element engage the slots, and the end of the receptacle lifts the workpieces out of the star-shaped delivery element. This transfer of the workpieces into the receptacle is generally known, but the removal of the workpieces from the star-shaped delivery element is significantly simplified because the workpieces are inserted into the star-shaped delivery element by the conveying and guiding unit with little force and consequently they are anchored less rigidly in the delivery element.
A tube or a tubular collection device is preferably connected to the receptacle. In one preferred embodiment, this tubular collection device is formed by several rods that are arranged parallel to one another and between which the workpieces are guided, if so required, with low friction. The friction can be adjusted such that the workpieces are held in a vertical alignment while not impairing the conveying process in the longitudinal direction of the connection device. The rods merely apply pointlike focus to the edges of the workpieces such that the frictional forces remain minimal. The use of rods provides the additional advantage that the cross section of the collection device can be optimally adapted to different cross-sectional shapes of the workpieces. Round workpieces, oval workpieces, rectangular workpieces, etc., can be collected and conveyed in this fashion.
According to one additional development of the invention, it is proposed that a conveyor device, in particular, a conveyor finger, is provided which engages the collection device and can be displaced in the direction of the longitudinal axis of the collection device. The workpieces in the collection device are additionally conveyed and/or ejected by means of this conveyor finger. After a certain quantity of workpieces are deposited behind the star-shaped delivery element or in the collection device, the conveyor finger is moved either into the star-shaped delivery element or into the collection device, respectively, and moves either with these workpieces or pushes these workpieces in the conveying direction until another defined quantity of workpieces is deposited, whereafter it pushes the remaining workpieces out of the collection device into a transfer cartridge arranged behind the collection device. After the filling process, this transfer cartridge is moved into the operating path of an ejector unit such that the workpieces in the transfer cartridge can be pushed into a filling cartridge by means of the ejector unit, in particular, a ram. This filling cartridge represents part of a packaging machine, which performs the final packaging of the workpieces in the filling cartridge.